Caption: Tim Armstrong, Chairman and CEO of AOL, talks at a media summit, Thursday, March 10, 2011 in New York. AOL said Thursday it will slash 900 jobs worldwide, or nearly 20 percent of its work force, partly to eliminate overlap that stems from its recent purchase of The Huffington Post. (AP Photo/Mark Lennihan)

“It was crazy, ’cause every time I was on the set in that costume, I became Hit Girl,” Moretz told Wired.com during an interview at a San Francisco hotel.

“And every time I had the bangs on and the little pigtails, I became Mindy…. It was a lot of fun to show the difference between Mindy and Hit Girl for me, ’cause it’s almost like an alternate personality.”

Throughout director Matthew Vaughn‘s roller coaster ride of a movie, Hit Girl gets all the good lines, capping every Tarantino-scale bloodletting with a foul-mouthed joke.

Moretz’s spirited delivery of those potty-mouth punch lines, and the glee and ease with which Hit Girl slices and dices bad guys, have stirred up a storm even as they’ve dazzled fanboys and moviegoers.

To prepare for the frenetic fight scenes, Moretz trained for months. She practiced gun-handling and learned how to use the swords and butterfly knives wielded with utter authority on-screen. Still, shooting the action sequences proved grueling, she said.

“You had no music, you had no slow motion — you only had, you know, about five seconds’ worth of one little bitty shot, and then you did it probably 10 times and then you move on,” she said.

“It was really hard, ’cause I would have to stay as Hit Girl, and I’d have to keep my face tough, and I’d have to be in the moment, you know, getting revenge — and then I’d have to think in my head, ‘OK, left foot, right foot, 1-2-3, jump!'”

The Kids of Kick-Ass

Hit Girl isn’t the only costumed crime-fighter in director Matthew Vaughn’s hyperviolent movie. Like Mark Millar and John Romita Jr.’s comic book upon which it’s based, Kick-Ass revolves around Dave Lizewski, a likeably dorky superhero wannabe who dons a wetsuit and takes a stand against criminals.

Kick-Ass and Red Mist cruise in the Mist Mobile.Photo: Dan SmithPortayed by 19-year old British actor Aaron Johnson, Dave, dressed as Kick-Ass, goes out on misguided adventures that land him in the hospital with life-threatening injuries. After a bystander films him squaring off against some street thugs, he becomes a media sensation

“Dave’s a sensitive guy,” said Johnson. “He’s lost his mother and he’s a nobody in school and he creates Kick-Ass as this whole different persona.”

In contrast to the in-control Hit Girl, Kick-Ass blunders his way through every encounter. His “superpower” draws from post-beating nerve damage that enables him to absorb an abnormal amount of body blows.

But Kick-Ass has his heart in the right place.

“He’s a kid who’s got balls to go out there and fucking do something different,” said Johnson, who spoke with Wired.com during the South by Southwest festival in Austin, Texas, following Kick-Ass‘ raucous premiere.

Also in Austin was Christopher Mintz-Plasse, 20, who plays the mysterious Red Mist. “We don’t have any of the action in the movie,” he said. “It’s all Hit Girl.”

Big Daddy’s Little Girl

And behind every child dynamo, there’s a mentor. For Hit Girl, it’s her father, Damon Macready, aka Big Daddy. Played with a perfect mix of humor and insanity by Nicolas Cage, the B-list Batman trains his daughter in the ways of violence, making him perhaps the world’s most questionable home-schooler. The father-daughter relationship is both charming and shocking: Their bond is based on love, yet the end result of all Damon’s teaching, planning and plotting is supremely brutal.

In a sequence that Moretz regards as the movie’s “emotional climax,” Big Daddy and Kick-Ass get tortured live on the internet. Not for the squeamish, it’s Moretz’s favorite scene.

“From the moment you see them getting beat up,” Moretz said, “you’re like, ‘There’s no one there that’s going to save them,’ and you basically know they’re going to die, until boom! — the lights are off, and you’re like, ‘Who could that be? And you think, ‘Oh, maybe it’s Hit Girl.’ And you see the little hands come up with the little goggles, and you realize it’s her.

“That was a scene where, even though I was Hit Girl, I really had to show that Hit Girl’s still an 11-year-old girl. Because the whole movie, you know, you’re kind of rooting her on to do the stuff she’s doing. You’re like: ‘OK, go! Go do it, go do it, go do it!’ And then, you know, it’s like ‘Boom’! And you realize, wow, Hit Girl’s — she’s 11, and we’re rooting her on to do this stuff, and she’s just a little kid.”

Hit Girl’s Final Showdown

The fact that Hit Girl is essentially a pint-size preteen whose brain has been filled with a deadly combination of training and comic-book violence fuels some of the movie’s most dramatic moments.

Case in point: Hit Girl’s ultimate showdown with crime boss Frank D’Amico (played by Mark Strong). After single-handedly slaying dozens of his men, Hit Girl gets booted by the lead gangster. “You get snapped back into reality when he kicks her in the face,” Moretz said. “You know, that’s really when she realizes, you know, it’s not playing with dolls. It’s not a comic book — it’s real life. I actually could die.”

The violent finale brought out concerns for Moretz from her co-stars when they saw the scene, which Johnson called “nasty.”

“The first hit,” he said, “kaboom, and you’re like [ewwwwww]. That’s disgusting.”

“It’s just so good,” Johnson continued, “because it’s one of those things where it gets to the point in the movie where he’s just like, ‘This fucking Hit Girl’s killed all my men, I fucking hate her. The kick — you just feel it, ’cause he just sees her as like another vicious bloke…. And then you look down, and then you see her lick at blood [on her face], and you’re just like, ‘That’s an innocent little girl!”

“But you see that in her face,” Johnson said. “That innocence just comes across ’cause she sees a bit of blood … which is what Matthew [the director] brings across … so it makes the whole audience just feel sick — and it’s brilliant.”

Moretz: Relax, It’s Just a Movie

The brutal fights and Hit Girl’s dirty talk has earned the ire of some movie reviewers, who raise concerns about Kick-Ass‘s potential impact on young viewers who manage to see the R-rated romp. U.K. newspaper The Daily Mail called the film a “crime against cinema” and said the movie is “twisted, cynical and revels in the abuse of childhood.”

Despite the ruckus, Moretz comes across as a pretty well-adjusted teenager who clearly groks the distinction between Hollywood fantasy and reality.

“At the end of the day, it’s still a movie,” said the actress, who will undoubtedly be known as Hit Girl from this point on. “It’s something that you sit down in a theater and watch. And, you know, it’s not meant to be re-enacted. I definitely don’t tell anybody to go out and do what Hit Girl does, or say what Hit Girl does. I would never in a million years want anyone to re-enact what I do or say in that movie — especially little kids.”